Optimum discharge control

ABSTRACT

A liquid receiver is adapted to rapidly receive, intermittently, large volumes of liquid. Liquid in the receiver is forwarded to a zone of use or processing zone. After the receiver is full, controls regulate the flow therefrom whereby it gradually increases to a maximum rate and subsequently gradually decreases after a predetermined portion of the receiver contents has been emptied. The flow control devices provide for gradual changes in rates of flow into a zone of use and for extended periods of slow at a uniform optimum rate despite the nonuniform manner of liquid accumulation in the receiver.

United States Patent Marvin A. Remke Bartlesville, Okla.

Dec. 24, 1968 Mar. 16, 1971 Phillips Petroleum Company [72] Inventor [2l Appl. No. [22] Filed [45] Patented [73] Assignee [54] OPTIMUM DISCHARGE CONTROL 12 Claims, 2 Drawing Figs.

[52] US. Cl 222/1, 137/396, 222/58 [51] Int. Cl. B67d 5/34 [50] Field of Search 222/1, 58,

56, 52; 137/395, 396, 403, 413, (Matthew) [56] References Cited UNITED STATES PATENTS 2,984,386 5/1961 White 222/58 2,984,387 5/1961 White 222/58 Primary Examiner-Stanley I-I. Tollberg Assistant Examiner-H. S. Lane Attorney- Pendleton, Neuman, Williams & Anderson LEA/v 32 AM/NE l4 QUICK UNI-DIRECTIONAL TIME FLOW L/QU/D EXHAUST FLOW CONTROL DELAY RECORDER A RECEIVER LC colvmo VALVE CONTROLLER B VALVE 7 K 8 I8 22 24 26 28 3O 4O 3 R 20 6 B 37 59 43 5 q I 4/ 16! l RICH AM/NE UM DISCHARGE CONTROL BACKGROUND OF THE INVENTION This invention relates to the control of flow from a liquid receiver or accumulator to a zone of use. More particularly, this invention relates to a method and apparatus for discharging liquid from a receiver to a zone of treatment at a uniform optimum flow rate for a large segment of the feeding cycle and in the absence of rapid changes in the rate of flow although the liquid receiver rapidly receives its contents intermittently.

In various chemical processes it is desirable that a large volume of liquid material which is accumulated rapidly and intermittently be fed in a substantially continuous manner into a processing zone. Thus, in the feeding of natural gasoline into an amine treater, condensed natural gasoline must be accumulated from a pipe line and passed into the treater. A pig or ball is passed through the pipe line at regular intervals, such as every 12 hours. The ball pushes condensed natural gasoline through the pipeline along with gas. The natural gasoline in the absence of flow control would arrive at the absorber in large slugs.

Prior to entering the absorber, however, the slugs are collected in a surge tank or receiver tank. It is obviously desirable to feed the gasoline from the receiver into the absorber at optimum flow rates and without any rapid changes in the rate of flow. The use of controls such as motor operated valves whose openings are regulated by a controller which is, in turn, actuated by the liquid level in a tank containing the material to be fed, is well known. However, the prior art does not suggest an apparatus which smoothly passes rapidly accumulated slugs of liquid into a processing zone without a rapid change in the rate of flow, as will hereinafter be described in greater detail.

It is an object of this invention, therefore, to provide a novel method and apparatus for feeding a liquid material from a liquid receiver or accumulator, which liquid is gathered over short time periods at spaced intervals. The liquid is fed in the absence of sharp changes in flow rate into a zone of use whereby the processing taking place in the zone of use may be carried out in an efiicient manner.

it is a further object of this invention to provide for the substantially continuous withdrawal of liquid material from a liquid accumulator wherein liquid is received at spaced time periods so as to enable an accumulator of small size to be employed despite the large total amounts of liquid received over a number of such time periods.

It is a further object of this invention to provide a method and apparatus for the passage of accumulated liquid from a receiver into a processing zone wherein the liquid is passed from the liquid receiver and enters such zone at the maximum or optimum rate at which it may be utilized therein for a large segment of the feeding cycle.

The above and other objects of this invention will become more apparent from the following detailed description when read in the light of the accompanying drawing and appended claims.

DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates diagrammatically one arrangement of apparatus for carrying out the process of my invention.

FIG. 2 schematically illustrates the component parts of two valve members employed in the diagram of FIG. 1.

Referring now more particularly to the drawing, a liquid receiver or surge tank is therein illustrated in communication with a natural gasoline pipe line 12. A pig or ball is passed through the line 12 at periodic intervals, such as l2 hour intervals, for purposes of pushing condensed'natural gasoline into the receiver. During the spaced pigging cycles, which may be of 20 minutes duration, large volumes of liquid are accumulated in the tank It). The gasoline in the tank It) is then fed in a desirably continuous manner into an absorber or amine treater 14 through line 37, pump 39, line 43, valve 38 and line ll.

The gasoline which has been accumulated in the receiver 10 should not be fed at such a high rate into the absorber l4 so as to upset the efficient working thereof. Means should therefore be provided to discharge the liquid contents of the receiver 30 into the absorber 14 in a manner in which rates of flow are changed gradually. Between pigging cycles, the contents of the receiver are completely or substantially completely dispensed into the absorber without rapid changes in flow rates before a new slug of liquid is received in the receiver from the pipe line 12. The rate of liquid passage into the absorber is desirably the rate which assures optimum efficiency, or feed rates approximating the same.

A controller 16 generates signals dependent on the level of liquid in tank 10. After the tank 10 is filled to a desirably high level, the control 16 will transmit a high" signal. Although the following description will be specific with respect to pneumatic signals, it should be appreciated that the method hereinafter described will function equally well with electrical or hydraulic apparatus in which the signals forwarded are hydraulic impulses or electronic signals, equivalents for the apparatus elements described being obvious to those skilled in the art. The pneumatic signal from the control 16 will pass through line 18 and through a quick exhaust control valve 20. As will be hereafter described, the transmitted signal will not be restricted in any way while passing through the control valve 20 prior to entering line 22. On passing from line 22 through the control valve 20 prior to entering line 22. On passing from line 22 through control valve 24, the signal will be restricted by opening 23, see FIG. 2, and the resulting restricted signal will pass by means of line 26 into time delay reservoir tank 28. This tank is of substantial volume and is unvented except through line 30.

In reservoir tank 28 the signal pressure will slowly increase because of thelarge volume of liquid in tank 10, and the resulting signal is transmitted from tank 28 through line 30 to flow recorder controller 32 having a pneumatic set point. Controller 32 is in communication with flow measurement assembly 34 by means of line 36 and is connected with threeway motor-operated valve 38 through line 40. Assembly 34 indicates by signals to controller recorder 32 the flow rate into the absorber l4. Three-way valve 38, governed by controller 32, determines the relative quantities of the liquid flow from the receiver lll which are passed into the absorber l4 and recycled to the tank 10 by means of line 44, since pump 39 is able to remove liquid from receiver 10 at a rate greater than the maximum flow into absorber 14.

The signal passing from the time delay tank 28 to the flow recorder controller 32 will gradually increase, resulting in a gradual increase in the opening permitting flow through the valve 3% into the absorber 14. As the gas signal generated by the level control 16 passes to the time delay tank 28, the flow recorder controller will gradually open the valve 38 to the maximum setting, thereby permitting the maximum flow into the absorber 14. Because of the time delay in signal transmission after the level in the tank 10 has begun to drop, the flow of the gasoline into the absorber 14 will be at a maximum rate. With continued level drop, the level control 16 will transmit signals representative of the falling level to the controls in series.

A pressure system will eventuate in which the pressure, in the line 18 is lower than the pressure in the line 22, the two lines 18 and 22 being in communication with opposed ports of the quick exhaust control valve 20. When this condition arises, gas will be vented from line 22 by valve 20 until the pressure in line 22 is slightly less than the pressure in line 18. Gas cannot flow directly from line 22 to line 18 because of the back pressure valve 48 disposed in the control valve 20, see FIG. 2. The control valve 20 will then continue to reduce the pressure in line 22 as the level in receiver 10 drops.

As the liquid level in the tank it) continues to drop, the intensity of the level-indicating signal transmitted by level coritrol 116 will continually weaken, resulting in a weaker signal being transmitted by time delay reservoir 28 to the flow recorder controller 32. Controller 32 then effects a smaller opening in the valve 38 communicating with the line 41 leading to the absorber 14;.

The operation of the control valve 20 in equalizing the pressures in lines 18 and 22 is as follows: As will be noted from PEG. 2, the path of the gas signal from line 18 through the control valve 21) is by way of junction 17, line 49, back pressure valve 48, line 54), junction 23, and line 22. The elements of valve 20 disposed between the valve stationary top 71, stationary bottom 61 and the stationary sides 75 and 76 are reciprocally movable with the alternate expansion of diaphragm chambers 62 and 70. When the pressure in line 18 is greater than the pressure in line 22, pressure will be exerted through line 68 to increase the pressure in chamber 75) over that of the pressure exerted from lines 22 and 60 into chamber 62. When the pressure in chamber 70 is greater than the pressure in chamber 62, the elements 80 within the outer walls 71, 76, 61 and 75 of valve 26 will be shifted to the lower position against stop 78 so that line 18 is aligned with line 49 at junction 17 and line 50 is aligned with line 22 at junction 21. When the pressure from line 22 through line 60 into chamber 62 is greater than the pressure in chamber 7i), the elements 80 within the walls of valve 20 will be moved to the upper position against stop 79. This will cause line -5 to come into alignment with line 22 at junction 21 and line 52 to come into alignment with line 58 which will vent pressure from line 22 through line 56, valve 46 and lines 52 and 58. Gas can only pass from line 49 through valve 48 into line 50 and only when elements 80 are in the lower position. Gas can only pass from line 22 through valve 46 into line 58 and only when the mechanism is in the upper position. FIG. 2, therefore, is representative of the condition of the control valve when the movable valve elements are in the lowered position. This is the normal valve condition during the discharge of the first portions of the liquid contents from the liquid receiver 10.

As the level within the receiver drops beyond a predetermined level, the control 16 will generate a correspondingly low pressure pneumatic signal pressure in line 18, and since time delay tank 28 retains high pressure gas the pressure in line 22 will exceed that in line 18. The pressure in line 22 will then pass through line 60 into the expandable chamber 62, raising the above-described movable valve components and venting the gas from line 22 which will pass through junction 21, line 56, and the discharge orifice 58. The pressure for regulating the flow recorder controller 32 will therefore be reduced to the pressure transmitted by the level control 16. This reduction is made possible by means of the unidirectional control valve 24 which enables pressure in the time delay reservoir 28 to pass through line 26 and line 64, bypassing restricted opening 23 of the valve. From line 64 the gas will pass into line 22, line 60 and chamber 62, raising the aforedescribed elements of the control valve 20 so that the gas in line 22 may be discharged through the vent orifice 58 until its pressure is slightly less than that in line 18.

The restricted opening 23 of the flow control valve 24 tends to slow the passage of the signal in line 22 entering the time delay reservoir 28 during the initial portion of the discharge of the liquid contents from the liquid receiver 10. Following venting of the gas from line 22 through the discharge orifice 58, the pressure in line 18 will again become greater than the pressure in line 22, resulting in lowering of the movable components of the control valve 20 into the position illustrated in FIG. 2 because of the pressure passing through line 68 and into upper diaphragm chamber 70. However, as the liquid level continues to fall in the liquid receiver 10, the pressure in line 18 will again become less than the pressure in line 22, resulting in reelevating of the reciprocally movable components of the control valve 20 in the manner described. Thus, in the course of the reciprocal movement of the components of valve 20, line 22 will be vented with the valve components in the raised position so that the pressures in line 22, line 26, and line 18 may become equal to that pressure of the signal transmitted by level control 16.

l. is seen, therefore, from the foregoing description that a method and apparatus have been provided which enable accumulated liquid, rapidly collected in a surge tank, to be fed at gradually increasing rates into a processing zone until a maximum rate of discharge is obtained. This constant maximum feed rate is maintained for a desirably large segment of the feeding cycle. The maximum feed rate predetermined by appropriate setting of controller recorder 32 which regulates valve 38. The rate of discharge from the receiver 10 is gradually lessened with the level fall in the tank, thereby providing discharge from an accumulator to a processing zone, such as the aforedescribed absorber without rapid changes in the rate of flow. The size of the restriction of valve 24, the size of time delay reservoir 28, and the setting of con troller 32 are variables enabling the rate of feed flc-w to be varied.

The size of the liquid receiver 10 need only be such as to contain the maximum volume which is to be held in tank 10 during a pigging cycle. The control valve 24 and the time delay reservoir 28 provide an initial gradual increase in the signal transmitted to the flow recorder controller 32 at the beginning of the signal transmission by the level control 16. The quick exhaust control valve 20 enables the feed-flow opening in the motor valve 38 to be gradually closed as the signal transmitted by the level control 16 diminishes in strength.

Thus, control elements are provided in the above-described combination which initially provide for a gradual increase in signal strength until a maximum flow of liquid material into a processing zone is attained. Other apparatus elements provide for a gradual reduction of flow into the processing zone until the contents of the liquid receiver have been substantially depleted and in condition for reception of a new slug of gasoline. in the event the liquid contents of the receiver 10 decrease to a predetermined minimum level, pump 39 will then recycle the contents back to the tank 10 in accordance with appropriate setting of the controls. The liquid level in the tank 10 at which the maximum or optimum rate of flow into absorber l4 begins to decrease may be regulated by the operator. The decrease in such flow rate is normally set to take place when tank 10 is one-half to one-quarter full. Thus a uniform optimum flow is carried out for a large portion of the feed cycle beginning at the termination of the gradual rate increase and ending at the commencement of the gradual reduction in flow rate.

It is apparent from the foregoing description that modifications may be made in the apparatus and method described, and it is intended that this invention be limited only by the scope of the appended claims.

I claim:

1. In a process for discharging liquid from a receiving zone into a liquid-processing zone, the steps comprising discharging liquid at a relatively low rate from said receiving zone when the volume of liquid in said receiving zone is low, collecting a relatively large volume of liquid during a short time in said receiving zone, then discharging liquid from said receiving zone at a gradually increasing rate into said processing zone until a predetermined maximum rate of discharge is attained, maintaining said maximum rate of discharge until a predetermined low amount of the contents in said receiving zone has been reached, and thereafter gradually decreasing the rate of discharge of said liquid from said receiving zone into said processing zone.

2. The process of claim 1 in which said gradual decrease commences after a level of about one-half to one-quarter of said vessel contents has been reached.

3. in a process for discharging liquid from a receiving vessel wherein liquid is accumulated rapidly at spaced time intervals and discharged into a processing zone without rapid changes in the rate of flow between said time intervals, the steps comprising discharging liquid from said vessel at a relatively low rate while the volume in said vessel is low discharging liquid from said vessel to said zone at a relatively low rate while the volume in said vessel is low, then accumulating at a high rate a a volume of liquid in said receiving vessel, discharging liquid from said receiving vessel at'a gradually increasing rate into said processing zone until a maximum rate of discharge is attained, maintaining said maximum rate of discharge until at least about one-half of the contents of said vessel has been bination'comprising, first means '-for rapidly accumulating large volumes of liquid at spaced time intervals, second means sensitive to the level of liquid in said first means adapted to generate signals representative of the liquid level in said first means; flow control means for said liquid material, disposed between said first means and such processing zone; time delay means adapted to receive signals from said second means and transmit signals from said second means to said flow control means after a time delay; said flow control means being responsive to the signals received from said time delay means.

6. The apparatus of claim 5 in combination with third means for restricting the signals transmitted between said second means and said time delay means.

7. 'In an apparatus for controlling the rate of flow of liquid transmitted by said signal restricting means is greater than the signal transmitted by said liquid level control, the reducing means being in communication with said level control and said restricting means whereby signals transmitted by said level control are passed through the reducing means prior to entering said restricting means. l 1

9. The apparatus of claim 8 in which said signals comprise pressure impulses and said reducing means comprises a quick exhaust valve which vents the pressure transmitted by said signal-restricting means until it is of lesser strength than the signal pressure transmitted by said level control; the venting occurring when the signal transmitted by said signal restricting means becomes greater than the signal transmitted by said level control.

10. In an apparatus for controlling the rate of flow of liquid from an accumulator into a processing zone, the combination comprising a liquid receivertank in communication with a liquid-conducting pipe line,'means for periodically driving liquid in said pipe line into said receiver tank, a liquid level control operatively connected to said receiver tank adapted to transmit pressure signals proportional to the level in said receiver tank, a quick exhaust control valve receiving pressure signals from said level control, a unidirectional control valve receiving pressure signals from said quick exhaust valve and allowing signal flow in one direction only through a restricted opening therein; a reservoir tank of predetermined volume adapted to receive, collect and transmit pressure signals from said unidirectional control valve, a flow control valve interposed between said receiver tank and said processing zone,

material from an accumulator into a processing zone, the

combination comprising a receiver for rapidly accumulating large volumes of liquid at spaced time intervals, means sensitive to the level in said receiver adapted to generate signals of an intensity representative of the liquid level in said receiver, control means for a flow opening disposed between said receiver and said processing zone, signal-regulating means for receiving and gradually increasing the intensity of such generated signals and forwarding such signals to the flow opening control means until a maximum flow is reached, and for gradually decreasing the intensity of such forwarded signals after such maximum flow has been established for a predetermined period of time.

8. In an apparatus for controlling the rate of flow of liquid from an accumulator into a processing zone, the combination comprising an accumulator for receiving a volume of liquid to be processed, a liquid level control responsive to the level in said accumulator and adapted to transmit signals having a strength representative of said level, means for restricting the signals transmitted by said level control, a signal time delay adapted to receive restricted signals from the signal-restricting means, valve means controlling the rate of flow between said accumulator and said processing zone, said valve means being operatively connected to said signal time delay and being responsive to signals transmitted by said signal time delay; means for gradually reducing the strength of the signals transmitted by said signal time delay after the strength of the signals the opening in said flow control valve being responsive to the pressure signals transmitted by said reservoir tank, said quick exhaust valve venting the pressure in said reservoir tank to adischarge zone when the pressure in said reservoir tank is greater than the pressure of the signal transmitted by said level control; said reservoir tank pressure being exhausted until it is substantially the same as that of the signal of said level control.

11. In an apparatus for controlling the rate of flow of liquid material from an accumulator into a processing zone, the combination comprising a receiver for rapidly accumulating large volumes of liquid at spaced time intervals, means sensitive to the level in said receiver adapted to generate signals of an intensity representative of the liquid level in said receiver, a control for a flow opening interposed between said receiver and said processing zone, signal control means for receiving, regulating and forwarding the signals generated by the level control means to the flow opening control; said flow opening control being responsive to the forwarded signals; said signal control means restricting the intensity of the signals representative of the liquid level in said receiver forwarded by the level sensitive means, and forwarding said signals after a time delay whereby saidflow opening may gradually increase.

12. The combination of claim l'lin which said signal control means gradually decreases the intensity of the signals transmitted to said flow opening control after the liquid level in the receiver and the intensity of the signal transmittedby said level control drops below a predetermined minimum. 

1. In a process for discharging liquid from a receiving zone into a liquid-processing zone, the steps comprising discharging liquid at a relatively low rate from said receiving zone when the volume of liquid in said receiving zone is low, collecting a relatively large volume of liquid during a short time in said receiving zone, then discharging liquid from said receiving zone at a gradually increasing rate into said processing zone until a predetermined maximum rate of discharge is attained, maintaining said maximum rate of discharge until a predetermined low amount of the contents in said receiving zone has been reached, and thereafter gradually decreasing the rate of discharge of said liquid from said receiving zone into said processing zone.
 2. The process of claim 1 in which said gradual decrease commences after a level of about one-half to one-quarter of said vessel contents has been reached.
 3. In a process for discharging liquid from a receiving vessel wherein liquid is accumulated rapidly at spaced time intervals and discharged into a processing zone without rapid changes in the rate of flow between said time intervals, the steps comprising discharging liquid from said vessel at a relatively low rate while the volume in said vessel is low discharging liquid from said vessel to said zone at a relatively low rate while the volume in said vessel is low, then accumulating at a high rate a volume of liquid in said receiving vessel, discharging liquid from said receiving vessel at a gradually increasing rate into said processing zone until a maximum rate of discharge is attained, maintaining said maximum rate of discharge until at least about one-half of the contents of said vessel has been discharged, and gradually decreasing the rate of discharge of said liquid from said receiving vessel into said processing zone until the liquid in said receiving vessel is substantially depleted.
 4. The process of claim 3 in which said receiving vessel is rapidly refilled after said substantial depletion, whereafter the discharge into said processing zone is gradually increased to said maximum rate.
 5. In an apparatus for controlling the rate of flow of liquid material from an accumulator into a processing zone the combination comprising, first means for rapidly accumulating large volumes of liquid at spaced time intervals, second means sensitive to the level of liquid in said first means adapted to generate signals representative of the liquid level in said first means; flow control means for said liquid material, disposed between said first means and such processing zone; time delay means adapted to receive signals from said second means and transmit signals from said second means to said flow control means after a time delay; said flow control means being responsive to the signals received from said time delay means.
 6. The apparatus of claim 5 in combination with third means for restricting the signals transmitted between said second means and said time delay means.
 7. In an apparatus for controlling the rate of flow of liquid material from an accumulator into a processing zone, the combination comprising a receiver for rapidly accumulating large volumes of liquid at spaced time intervals, means sensitive to the level in said receiver adapted to generate signals of an intensity representative of the liquid level in said receiver, control means for a flow opening disposEd between said receiver and said processing zone, signal-regulating means for receiving and gradually increasing the intensity of such generated signals and forwarding such signals to the flow opening control means until a maximum flow is reached, and for gradually decreasing the intensity of such forwarded signals after such maximum flow has been established for a predetermined period of time.
 8. In an apparatus for controlling the rate of flow of liquid from an accumulator into a processing zone, the combination comprising an accumulator for receiving a volume of liquid to be processed, a liquid level control responsive to the level in said accumulator and adapted to transmit signals having a strength representative of said level, means for restricting the signals transmitted by said level control, a signal time delay adapted to receive restricted signals from the signal-restricting means, valve means controlling the rate of flow between said accumulator and said processing zone, said valve means being operatively connected to said signal time delay and being responsive to signals transmitted by said signal time delay; means for gradually reducing the strength of the signals transmitted by said signal time delay after the strength of the signals transmitted by said signal restricting means is greater than the signal transmitted by said liquid level control, the reducing means being in communication with said level control and said restricting means whereby signals transmitted by said level control are passed through the reducing means prior to entering said restricting means.
 9. The apparatus of claim 8 in which said signals comprise pressure impulses and said reducing means comprises a quick exhaust valve which vents the pressure transmitted by said signal-restricting means until it is of lesser strength than the signal pressure transmitted by said level control; the venting occurring when the signal transmitted by said signal restricting means becomes greater than the signal transmitted by said level control.
 10. In an apparatus for controlling the rate of flow of liquid from an accumulator into a processing zone, the combination comprising a liquid receiver tank in communication with a liquid-conducting pipe line, means for periodically driving liquid in said pipe line into said receiver tank, a liquid level control operatively connected to said receiver tank adapted to transmit pressure signals proportional to the level in said receiver tank, a quick exhaust control valve receiving pressure signals from said level control, a unidirectional control valve receiving pressure signals from said quick exhaust valve and allowing signal flow in one direction only through a restricted opening therein; a reservoir tank of predetermined volume adapted to receive, collect and transmit pressure signals from said unidirectional control valve, a flow control valve interposed between said receiver tank and said processing zone, the opening in said flow control valve being responsive to the pressure signals transmitted by said reservoir tank, said quick exhaust valve venting the pressure in said reservoir tank to a discharge zone when the pressure in said reservoir tank is greater than the pressure of the signal transmitted by said level control; said reservoir tank pressure being exhausted until it is substantially the same as that of the signal of said level control.
 11. In an apparatus for controlling the rate of flow of liquid material from an accumulator into a processing zone, the combination comprising a receiver for rapidly accumulating large volumes of liquid at spaced time intervals, means sensitive to the level in said receiver adapted to generate signals of an intensity representative of the liquid level in said receiver, a control for a flow opening interposed between said receiver and said processing zone, signal control means for receiving, regulating and forwarding the signals generated by the level control means to the flow opening control; said flow openiNg control being responsive to the forwarded signals; said signal control means restricting the intensity of the signals representative of the liquid level in said receiver forwarded by the level sensitive means, and forwarding said signals after a time delay whereby said flow opening may gradually increase.
 12. The combination of claim 11 in which said signal control means gradually decreases the intensity of the signals transmitted to said flow opening control after the liquid level in the receiver and the intensity of the signal transmitted by said level control drops below a predetermined minimum. 